Underscore Source Notes

Problem

1, (). Call (this) what does it mean?

2, _.noconflict () How to use?

3, obj through wrapper into _,wrapper object prototype has all the methods of underscore, _ more than obj These methods, this inheritance belongs to the inheritance of the constructor or the inheritance of the prototype chain?

4. What is the use of module in Nodejs? Why do you have to judge it? The underscore named variable is placed in each module of the exports, why different exports.

5, iterator how to use?

Knowledge points

1, the built-in object's prototype chain, the common method caches the local variable.

2. The method supported by the host environment, denoted by native.

3. Differentiate between Nodejs and browsers

if (typeof exports!== ' undefined ') {    //nodejs}else{    //browser}

4. Area score groups and objects

if (obj.length = = = +obj.length) {    //array}else{    //object}

5. Determine if an element is in an array

if (i in array)

6. Determine if obj has this key

if (_.has (obj, key)) {

}

Underscore Source Notes