57 lines
1.3 KiB
JavaScript
57 lines
1.3 KiB
JavaScript
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/* eslint no-console:0 */
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// parent node types that we don't want to remove pointless initializations from (because it breaks hoisting)
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const BLOCKED = ['ForStatement', 'WhileStatement']; // 'IfStatement', 'SwitchStatement'
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/** Removes var initialization to `void 0`, which Babel adds for TDZ strictness. */
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export default (file, api) => {
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let { jscodeshift } = api,
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found = 0;
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let code = jscodeshift(file.source)
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.find(jscodeshift.VariableDeclaration)
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.forEach(handleDeclaration);
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function handleDeclaration(decl) {
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let p = decl,
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remove = true;
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while ((p = p.parentPath)) {
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if (~BLOCKED.indexOf(p.value.type)) {
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remove = false;
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break;
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}
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}
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decl.value.declarations.filter(isPointless).forEach( node => {
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if (remove===false) {
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console.log(`> Skipping removal of undefined init for "${node.id.name}": within ${p.value.type}`);
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}
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else {
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removeNodeInitialization(node);
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}
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});
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}
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function removeNodeInitialization(node) {
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node.init = null;
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found++;
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}
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function isPointless(node) {
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let { init } = node;
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if (init) {
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if (init.type==='UnaryExpression' && init.operator==='void' && init.argument.value==0) {
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return true;
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}
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if (init.type==='Identifier' && init.name==='undefined') {
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return true;
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}
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}
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return false;
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}
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return found ? code.toSource({ quote: 'single' }) : null;
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};
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